


Mutual Benefits

by Anonymous



Series: Mutual Benefits [1]
Category: Supernatural
Genre: BMOL are assholes, Bondage, Breathplay, Caring Castiel (Supernatural), Consensual Sex, Friends With Benefits, Other, Past Hurt Castiel, Past Hurt Sam, Past Hurt Tenacle Monster, Past Hurt/Comfort, Reference to Past Panic Attack (Cas), Tentacle Sex, Tentacles, That’s a tag I never thought I’d use
Language: English
Status: Completed
Published: 2019-02-16
Updated: 2019-02-16
Packaged: 2019-10-29 14:12:54
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 1,662
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/17809451
Author URL: https://archiveofourown.org/
Summary: The guys find a hidden room in the bunker that has been home to an imprisoned tentacle monster for a long time.But it’s a very friendly tentacle monster, from another dimension, and it only eats one thing.Dean and the tentacle monster come to a mutually beneficial arrangement.





	Mutual Benefits

**Author's Note:**

> So everything herein is fully consensual. The tentacle monster is perfectly happy staying in its room in the bunker with its new friends, and Dean is happy to provide it with the sustenance it needs. 
> 
> The past hurt comfort for Sam and Cas is just referenced, but if you’re claustrophobic or find Cas being triggered by a situation reflecting past trauma, or him being kind of mummified, please bear in mind this story references both of those things happening.

Dean knocked once at the door, and stepped inside when he heard a wet _gurgle_ in response.

“Hey,” he greeted. He waved a large, paperbound package into the semi darkness, and set it down on the small table he and Sam had set up in the corner. “Cas is still worried about you getting cold down here, so he knitted you a scarf. I know, I don’t know how that’s going to work, but he insisted. Your mileage may vary.”

Something shifted further back in the room, a wet-inching-closer kind of sound, and in the time it took Dean to close the door behind him, the package had been picked up and quickly, but carefully, unwrapped.

Cas’s scarf, long and wide, and shades of red, purple and blue, dangled, undergoing a thorough examination, and then vanished into the shadows.

The sound he heard, to anyone else (like anyone else wouldn’t have bolted by now) would have dredged up hind-brain memories of something slip-slopping against cold, damp walls and floor, followed up by a repeated slapping sound like thick flesh on stone.

Dean grinned into the not quite darkness; his eyes were growing accustomed to the insufficient light. “Yeah, got it, I’ll tell him. But you might wanna take it off, if we’re, uh….”

The slapping sound came again, and the scarf, balled up carefully, came flying out at him.

Dean caught it, easily, and set it down on the table.

He heard that sound again, a little impatient this time, and started to take off his shirt, toeing off his sneakers at the same time.

“I know,” he said, upon hearing a grumbling, petulant _gurgle_. “Hunt took a little longer than we thought. I’ll make it up to you.”

There was an expectant silence and then a long, thin shape slowly undulated its way towards him, and flicked at the hem of his tee-shirt.

Dean huffed at the cold tip that brushed his skin, knowing he wouldn’t mind it in a while, and didn’t resist the help. He lifted his arms, let the tentacle tug the tee up and over, and then it was tossed over his head in a well aimed throw that draped it over Cas’s scarf.

He managed his jeans himself, folding them and putting them aside as well, then took care of his underwear and socks.

And then he was naked, and cold, and more aware than ever of being watched.

The tentacle stroked gently down his cheek, along his jaw, and curved lightly around the back of his neck.

Dean turned his head enough to brush it with his lips, more affection than lust, and grinned at the tremble he felt through it.

“It’s okay,” he said. “Gonna let you take what you need.”

++

After a few years in the bunker, none of them thought it could possibly hold any more surprises.

There was the room with the painting on the back wall, a medieval garden scene that changed, like something out of Harry Potter, with the seasons.

There was the room that was like a series of those stacking Russian Dolls, where Sam had almost got crushed before they realised that it wasn’t just each door getting narrower behind him, but the rooms themselves as he worked his way further into the fucked up layout, which had convinced Dean more than ever that the MOL had been psychotic bastards.

And then there was the room that Cas went into and couldn’t get out of, hitherto invisible markings around the inside of the door flaring into life, spreading across the walls, which suddenly exuded thick black webbing that sprang out and snared the angel.

Not only could Cas not get out, but they couldn’t get in, because apparently that was a room designed to hold angels and keep humans safe from them.

And that horrific gunk holding him reminded them all, Cas especially, of other things and that was the first time Dean had ever seen Cas have a full on panic attack.

Lucky for them that Ketch had dropped by for a chance to rest and to bring them an artefact that might provide an extra layer of bunker-protection against rogue archangels and their hodgepodge monster army.

He’d known how to deactivate the sigils, letting them into the room, but they’d all had to cut Cas out and spent the better part of an hour peeling that shit off the angel, who’d by then retreated so far into himself that Dean thought they’d never get him back out.

After, Dean had been both grateful and grudging of the help they’d received, that _Ketch_ had been the one to save Cas, and then reveal that touching a shell shocked angel on the nape of the neck would bring them around. It should have been them doing all that for Cas, and he’d said as much to Sam, who’d rebuked him; did it matter who, as long as Cas was okay?

But later, Sam had admitted he got it too. Keeping Cas safe was their responsibility, he was their family, and neither of them really trusted Ketch, even after that.

Still, it was the last room they stumbled upon, because Sam found a vague reference to it in a bundle of reports on the bunker’s upkeep from who knew when (the writing was old, stylish, and faded to near nothing in places).

So, because the idea of another hidden room was too troubling to leave it alone, they’d explored.

And this was what they’d found.

It still gave Dean nightmares, about being trapped alone for years in the dark, knowing no one was going to come and let you out.

Especially given the shit fest his life had been the past few months. 

But when they’d found it, it’d been in a state of dormancy, forced into it to survive since no one had been near it, fed it, in such a long time.

Even so, it’d shown remarkable restraint, never touching any of them, and making it very clear it wasn’t going to do them any harm.

Cas found a battered old book in the same place as the reports, and it was written in some kind of code, but code was just another language, and Cas was easily able to translate it.

The MOL had captured their secret guest during a foray into another reality, and dragged it back here, and kept it prisoner ever since.

And as for how to care for it…. Cas had tilted his head, and looked at Dean, and said, “I think I might have got a word wrong.”

But angels didn’t get words wrong.

++

It holds the human a few feet off the ground, marvelling at the trust he shows; his heart is racing, but it’s need, and excitement, not fear, and when he wriggles and tenses, it’s not a desire to escape.

This is like a fantasy for him, being taken and rendered helpless, so it tries to make it as good as it can for him. Squeezes a little tighter, not enough to hurt, holding his arms pinned at the small of his back.

It wraps around the jutting erection, stroking, growing bolder as the human moans an encouragement. The narrowest of its tentacles is able to slip inside the tiny opening there, and it dips in, not too far, and the human almost screams.

Sustenance bubbles up around its tentacle, and it reaches out with its long tongue to lap it up. There’ll be more soon; he knows that the human keeps itself for him, now, and its shows its gratitude accordingly.

One of its thicker appendages nudges against the human’s cleft, pushing into the hidden heat, slicking up the passage as it edges in deeper.

The human jerks a little, this part is always trickier, because it has to be in him to ease the way, but he distracts it by gently curling another of its tentacles around the nubs of flesh on its front.

That also produces a satisfying reaction, and by the time those tiny bumps are hard beneath its ministrations, the going is easy.

It pushes in and withdraws, never all the way, setting up a rhythm the human finds pleasurable.

His mouth is open, eyes squeezed shut, so inviting, and it knows what else he likes.

It picks the appendage carefully; too thin, it could go too far down. Too thick, it might cause damage. Once it’s sure, it sinks another tentacle between his lips, wriggling lower until it knows it’s blocking that channel.

Then it starts to thrust harder into him, faster, knowing it has to be quick now.

The human is silenced, but shaking, tugging helplessly against the tentacles coiled around his arms and legs, but then shudders violently as his release comes.

Again, it tongues up the delicious liquid spattering out of him, not wasting a drop, and removes itself from his throat, listening carefully for his breathing to return to normal.

It eases out of him, and sets him carefully on his feet, holding him there long enough to be sure he’s steady and at no risk of falling.

There’s a polite knock at the door. The angel, it realises, who will take over now, and take the human and make sure he’s cared for in ways that it can’t.

It strokes his cheek, again, the only way it can show its gratitude, and seek reassurance that the human is alright.

The human pats it, grinning, though he looks tired. “Thanks,” he says, and then he grabs up his things. “Couple of days, okay?”

It waggles its tentacle in the gesture it’s seen the humans, and the angel, do with their heads, and then it’s alone again.

It’s not like before, though. Its new family is either along the hall, or upstairs, two humans and an angel.

For the first time in as long as it can remember, this isn’t its prison anymore.

Now, this is its home.


End file.
